Albedo

As usual, there is more to learn in the CERES satellite dataset. I got to thinking of the idea put forth by Lacis 2010. He announced model results claiming that if the only modeled greenhouse gas in the modeled atmosphere were modeled water, the model world would basically evolve to a modeled ice over condition at a modeled -20°C (-4°F). Here is his money graph, showing the evolution of various modeled climate measurements in the first fifty modeled years after removing all modeled GHGs except for modeled water from the modeled atmosphere. See his paper for details.

After the turn of the century, I became interested in climate science. But unlike almost everyone else, I wasn’t surprised by how much the global temperature was changing. As someone with experience with heat engines and engine governors, I know how hard it is to keep a heat engine stable under a changing load. As a result, I was surprised at how little the temperature was changing.

Over the 20th Century, for example, the temperature changed by a trivially small ±0.3°C. Since the average temperature of the planet is on the order of 287K, this means that the global temperature varied only about a tenth of one percent in a hundred years … that that is amazingly stable.

The CERES satellite dataset is a never-ending source of amazement and interest. I got to thinking about how much energy is actually stoking the immense climate engine. Of course, virtually all the energy comes from the sun. (There is a bit of geothermal, but it’s much less than a watt per square metre on average so we can ignore it for this type of analysis).

So let’s start from the start, at the top of the atmosphere. Here’s the downwelling top of atmosphere (TOA) solar energy for the northern and the southern hemisphere:

Figure 1. Top of atmosphere (TOA) downwelling solar energy. This is averaged on a 24/7 basis over the entire surface of the earth.